Not sure about camping on LBJ. My brother has a couple of rent houses on the lake. The Pencil House is well known for its pencil colored carved tree limbs. We want to camp at Inks Lake State Park. No,far away, and the upper lake to LBJ. Lake Marble Falls has an RV park at Hwy. 281 and Lake Marble Falls.
Fredricksburg RV Park was nice, we also stayed at Quiet Cove in Fredricksburg over Christmas break.
Have fun!